A six-axis force sensor has been proposed in Japanese Patent Application Laying-Open Publication No. 2003-254843 (JP 2003-254843 A). The proposed six-axis force sensor has a shock absorbing device provided to a periphery of a six-axis force sensor chip in order to minimize the magnitude of an external force that is applied to an external force application part (force action part) of the six-axis force sensor chip, which is manufactured using a semiconductor substrate. The level of the external force that can be measured by the six-axis force sensor is thereby dramatically increased, and the range of application can be increased. Further, problems related to multiaxial interference can also be resolved even when the structure of the six-axis force sensor has a shock absorbing device.
A load detector disclosed in Japanese Patent Application Laying-Open Publication No. 5-118943 (JP 05-118943 A) has an annular rigid part positioned on an outer periphery thereof; a rigid part positioned in the center thereof; and a radially provided load detection part, which connects the two rigid parts. Holes, notches, grooves, or the like are formed in the load detection part, making it possible to align the gain of the axial components of the detected load.
A semiconductor sensor chip obtained using a semiconductor manufacturing technique may be used as a component for sensing force and moment in the force sensor described above. A semiconductor substrate is used, and a component for receiving an external force (force action part) is formed in the semiconductor sensor chip. Accordingly, an upper limit also exists in regard to the amount of force that can be applied, and a risk is presented in that the semiconductor substrate chip may be damaged when the chip is subjected to an unnecessarily large force or moment.
Since no force can be detected if none is transmitted to the chip, a shock absorbing device having an external force damping mechanism for appropriately damping external forces is preferably provided so that a necessary and appropriate amount of the external force inputted to the input part of the sensor can be transmitted to the chip.
The external force damping performance of the external force damping mechanism of the shock absorbing device is conventionally determined in relation to the shape and structure of the external force damping mechanism, e.g., by manufacturing a complex shape or forming holes. However, it has not generally been possible to readily adjust the damping characteristics of the damping mechanism.
In the parts that connect the shock absorbing device and the force sensor chip, a portion of the external force is transmitted from the external force transmitting part of the shock absorbing device to the force action part of the force sensor chip via the joining surface between the shock absorbing device and the force sensor chip. A chip seat part that supports and secures the force sensor chip in place is ordinarily secured in place using a securing part of the shock absorbing device. Accordingly, a risk is presented that the application of external force may cause deformation as far as the joining surface between the chip seat part and the securing part of the shock absorbing device. As a result, in a conventional force sensor provided with a shock absorbing device, a risk is presented that delamination may occur at the joining surface between the chip seat and the securing part of the shock absorbing device.